Sorry didn't see your thread.
Shape does matter! Martin King, using his MathCad application has demonstrated that. Long enclosures with driver at one end and port at the other acts like a transmission line. Long enclosures with driver near the middle and port at the end acts like a pipe. This is physics, not nomenclature. Slight deviations shouldn't matter much.
Consider the simplest example of a sealed cabinet in a room. Both the cabinet and the room are enclosures with the driver creating sound into both. Beyond the transmission line/pipe concerns a cubic or spherical enclosure would have a similar severe echo problems as a cubic or spherical room. So the principles governing the ideal shape for a room and a cabinet should be the very similiar.
First reflections off the back wall of the cabinet is more intense than first reflections off side wall/floor/ceiling (don't believe an inch of absorptive material will do anymore in the cabinet than it does in the room). Keep in mind that the most acoustically transparent surface of the cabinet is the driver cone, so those severe reflections come right back through the driver but with a slightly out of phase and somewhat muffled sound wave, especially if the back cabinet wall is parallel to the front baffle.
Check Dave's Planet 10 website for excellent (very bass effective) cabinet designs (he works extensively with Mark Audio drivers). Check the Single Driver Circle.
